The deployment of wireless local area networks (WLANs) in the home, the office, and various public facilities is commonplace today. Such networks typically employ a wireless access point (AP) that connects a number of wireless stations (STAs) in a specific locality (e.g., home, office, public facility, etc.) to another network, such as the Internet or the like. A set of STAs can communicate with each other through a common AP in what is referred to as a basic service set (BSS). However, some WLAN network deployments may be dense (e.g., have a large number of STAs deployed within the coverage area of multiple APs), which may result in issues related to channel or medium usage. In other examples, the wireless network may be configured as an “ad-hoc” communication system in which terminals asynchronously communication directly with each other without use of any specific AP.
With multiple STAs and APs operating in a limited area, traffic collisions and interferences may occur among STAs and/or APs attempting to access the wireless medium. The traffic collisions and interferences may cause packets to be dropped where the transmitting device may be required to retransmit the same packet multiple times before successful transmission. However, because wireless STAs are usually small handheld devices operating on a limited power source (e.g., small battery), the STAs may need to balance consideration of power consumption against repeated transmission attempts. Various techniques and systems have been developed to minimize traffic collisions and power consumption of the STAs.
One such technique includes operating the STA, for example, in a power save operating mode. The power save operating mode allows the STAs to enter a sleep mode and wake-up periodically to listen to an AP's beacon. The AP may buffer packets for a particular STA if the target STA is in a sleep mode, and notifies the STA of the availability of pending packets in the beacon frame. When the STA wakes up, the STA may decode the beacon to determine if there are pending packets for the STA, and if so, transmit a trigger frame to the AP to initiate downlink transmission from the AP to deliver the buffered packets to the STA.
Alternatively, an AP, motivated by limiting traffic collisions, may similarly apply trigger frames to schedule uplink traffic from a plurality of STAs. However, conventional trigger frame techniques suffer from a number of drawbacks, including high overhead that includes redundant information for each STA separately. Further, the present techniques require the device receiving the trigger frame (e.g., STA) to decode the entire trigger frame regardless of whether or not the frame was directed to the decoding the STA. Such implementation may be highly inefficient and power intensive.